91影视

Rolling dice Suppose you roll two fair, six-sided dice鈥攐ne red and one green. Are the events 鈥渟um is 7鈥� and 鈥済reen die shows a 4鈥� independent? Justify your answer. (See Figure 5.2 on page 314 for the sample space of this chance process.)

Rolling dice Suppose you roll two fair, six-sided dice鈥攐ne red and one green. Are the events 鈥渟um is 8鈥� and 鈥済reen die shows a 4鈥� independent? Justify your answer. (See Figure 5.2 on page 314 for the sample space of this chance process.)

Free downloads? Illegal music downloading is a big problem: 29% of Internet users download music files, and 67% of downloaders say they don鈥檛 care if the music is copyrighted. 18 Find the probability that a randomly selected Internet user downloads music and doesn鈥檛 care if it鈥檚 copyrighted.

. At the gym Suppose that 10% of adults belong to health clubs, and 40% of these health club members go to the club at least twice a week. Find the probability that a randomly selected adult belongs to a health club and goes there at least twice a week.

Box of chocolates According to Forrest Gump, 鈥淟ife is like a box of chocolates. You never know what you鈥檙e gonna get.鈥� Suppose a candymaker offers a special 鈥淕ump box鈥� with 20 chocolate candies that look alike. In fact, 14 of the candies have soft centers and 6 have hard centers. Suppose you choose 3 of the candies from a Gump box at random. Find the probability that all three candies have soft centers

Due to a hit A very good professional baseball player gets a hit about $35\%$ of the time

over an entire season. After the player failed to hit safely in six straight at-bats, a TV

As one commentator said, 鈥淗e is due for a hit.鈥� Explain why the commentator is wrong.

Sampling students A statistics class with 30 students has 10 males and 20 females. Suppose you choose 3 of the students in the class at random. Find the probability that all three are female.

Fill 鈥檈r up! In a certain month, 88% of automobile drivers filled their vehicles with regular gasoline, 2% purchased midgrade gas, and 10% bought premium gas. 19 Of those who bought regular gas, 28% paid with a credit card; of customers who bought midgrade and premium gas, 34% and 42%, respectively, paid with a credit card. Suppose we select a customer at random. a. Draw a tree diagram to model this chance process.

b. Find the probability that the customer paid with a credit card.

c. Suppose the chosen customer paid with a credit card. What鈥檚 the probability that the customer bought premium gas?

Media usage and good grades The Kaiser Family Foundation released a study about the influence of media in the lives of young people aged 8鈭�18. 20 In the study, 17% of the youth were classified as light media users, 62% were classified as moderate media users, and 21% were classified as heavy media users. Of the light users who responded, 74% described their grades as good (A鈥檚 and B鈥檚), while only 68% of the moderate users and 52% of the heavy users described their grades as good. Suppose that we select one young person from the study at random.

a. Draw a tree diagram to model this chance process.

b. Find the probability that this person describes his or her grades as good.

c. Suppose the chosen person describes his or her grades as good. What鈥檚 the probability that he or she is a heavy user of media?

First serve Tennis great Andy Murray made 60% of his first serves in a recent season. When Murray made his first serve, he won 76% of the points. When Murray missed his first serve and had to serve again, he won only 54% of the points. 21 Suppose you randomly choose a point on which Murray served. You get distracted before seeing his first serve but look up in time to see Murray win the point. What鈥檚 the probability that he missed his first serve?